a. Field of the Invention
The present invention relates to monitored and controlled systems, and more particularly to a computer monitored or controlled system the operational configuration of which may be modified on-line.
b. Brief Description of the Prior Art
Many systems are available which permit the operating configuration of a monitored or controlled system to be automatically established. Typically, a systems engineer defines the operating configuration which he desires to achieve by filling in blanks on coding forms and by feeding data from the coding forms into an automatically programmable computer system. Particularly in the field of data monitoring, relatively complex operating configurations may be achieved in this manner.
However, once a system is established and operating, typically it is difficult to modify the operating configuration of a system. After compilation or assembly, conventional computer programs no longer contain the meaningful names for variables and for subroutines which they contain prior to assembly and it is almost impossible for anyone save a skilled programmer to interpret the data which a typical computer system spills forth as its contents. Hence, one who wishes to work with such a system is dependent upon whatever documentation of the system operating configuration is available. If the documentation is lost, destroyed, or erroneous, then typically a prior art system must be reconfigured in its entirety when any changes are made.
In prior art systems, the compilation of software entities is a one-way, irreversible process. Once a program system is established and operating, there is no way that the system may regenerate the language originally written out by a systems engineer or programmer--that language is lost. Only numeric machine language remains which is understandable only to the machine itself.
In prior art systems, modifications are made by altering computer programs written in a language such as FORTRAN IV. Once a modified program has been prepared, it is compiled, fed into the operating system, and the program which it replaces is removed from the operating system. Typically a skilled programmer has to make such modifications. Programs may to some extent be tested and debugged using a time sharing computer which stores programs in their uncompiled form, but no such editing may normally be carried out on a monitoring or control computer due to their limited memory size and the impossibility of storing uncompiled copies of all programs in such a machine.
The need for an easily editable system is particularly acute in process control systems where most of the programming is conventional as opposed to fill-in-the-blank programming. Even in the so-called "interpretive" systems where control operations are defined by interpretable data files, there is typically no way of reconstructing from any given data file the language which was originally used by a systems engineer to define the data file.